The present invention relates generally to a system for cleaning the front nozzle face of an ink jet printhead with a wiper blade system and, more particularly, to a system and method for cleaning of the nozzle face of a color printhead having separate recording segments.
An ink jet printer of the so-called "drop-on-demand" type has at least one printhead from which droplets of ink are directed towards a recording medium. Within the printhead, the ink may be contained in a plurality of channels and energy pulses are used to cause the droplets of ink to be expelled, as required, from orifices at the ends of the channels.
In a thermal ink jet printer, the energy pulses are usually produced by resistors, each located in a respective one of the channels, which are individually addressable by current pulses to heat and momentarily vaporize ink in the channels which contact the resistors. Operation of a thermal ink jet printer is described in, for example, U.S. Pat. No. 4,849,774.
It has been recognized that there is a need to maintain the ink ejecting orifices of an ink jet printer, for example, by periodically cleaning the orifices when the printer is in use, and/or by capping the printhead when the printer is out of use or is idle for extended periods. The capping of the printhead is intended to prevent the ink in the printhead from drying out. There is also a need to prime a printhead before use, to ensure that the printhead channels are completely filled with ink and contain no contaminants or air bubbles Maintenance and/or priming stations for the printheads of various types of ink jet printers are described in, for example, U.S. Pat. Nos. 4,855,764, 4,853,717, 4,746,938 and 5,151,715.
For color ink jet printers, separate printheads are mounted on a print carriage, each printhead supplied by ink of a particular color. The printheads are selectively driven to produce recording swaths of color images forming a full color image.
The colors of the ink used are usually cyan, magenta, yellow and black. The cleaning of the nozzle faces for different colored printheads becomes complicated since, if a single cleaning means, such as a single wiper blade is used to wipe across the front face of the printhead, the wiper blades carries a mixed colored ink residue which may overlap and be transferred back into the nozzles and effect the next droplet ejection from that nozzle. U.S. Pat. 5,182,582 describes one solution to this problem wherein the nozzle faces are cleaned and arranged so that the nozzle faces are cleaned in the order of from lighter to darker inks.
A cleaning problem still exists for multi-color ink jet printheads of the type wherein a single printhead die is segmented into sectors or groups of nozzles, each sector or group being fluidly connected to an ink reservoir for a particular associated ink recording color.
For this configuration, there are boundaries between printhead groups or sectors, and nozzles on both sides of the boundary are susceptible to contamination by ink from the adjoining sector. A simple wiping blade which wipes across the face of the nozzle inevitably causes some transfer and mixing of ink from colored ink nozzles adjacent the boundary sectors into ink of the adjoining color sector. This problem is exacerbated if the nozzle faces are oriented in a vertical plane since the effects of gravity will contribute to contamination of the nozzles immediately below a sector dividing boundary.